Both players had already defeated Zhang Shuai in their opening matches of the Camellia Group, thus giving the encounter the feel of a knockout match. It proved a rollercoaster affair, with the momentum starting with the higher-ranked player before shifting to her 25-year-old opponent then back again.

And there was even a late twist as Sevastova, with victory seemingly in her hands, allowed three match points to slip away against a tenacious opponent, whose will to win was remarkable.

"These matches are the ones that really count. It's long, it's difficult, you have match points against you, you don’t lose your courage, you don’t lose your enthusiasm. And it worked today," she said on court after the match.

It was the WTA World No.11 who made the better start to the match, persistently outworking her opponent, whose power game was misfiring.

Sevastova eased to a 4-1 lead, prompting a feisty exchange between Muguruza and her coach at the change of ends, yet this was the catalyst for the Spaniard to produce her best tennis.

She increasingly visited the net and for the first time, she was playing the match on her terms. Although she passed up one fine break point opportunity as she hit into the net with half the court to hit, she was soon level.

Sevastova stopped a three-game rot to move ahead 5-4, then got her nose into the lead once more at 6-5. What followed was an incredible 10-minute, 20-point game that Muguruza struggled to put away before finally forcing the tiebreak.

In that decisive game, both players started explosively, with some stunning exchanges. Sevastova, however, showed greater aggression and consistency to take it 7-4, much to the frustration of her opponent.

"I think I did a good job of trying to deal with that and turn it into something positive to start the second set better," she said.

After a first set that lasted comfortably over an hour, Muguruza was halfway to winning the second within nine minutes, winning the opening three games for the loss of just three points.

Within the blink of an eye, she was 5-0 up, and only a precise ace, deft dropshot and fine lob prevented Sevastova from losing just a second set of 2018 to love, having been just a point away from doing so.

Her blushes were further spared as she earned another game back, but Muguruza took the set 6-2.

Following treatment on her back between the second and third, Sevastova came out for the decider firing on all cylinders. She established a 2-0 lead but by the midway point in the set, the players were locked as Muguruza won three successive games once more.

A remarkable set moved back in the favor of the Latvian as she broke in the ninth game, but she faced tremendous resolve from Muguruza as she served for the match. Three match points in total came and went, the last as the Spaniard cracked a dramatic winner down the line before going on to break.

There was drama in the following game, too, as Sevastova saw a break point slip away, although she did force the tiebreak by subsequently holding serve.

The momentum, though, was with Muguruza, who dominated the additional game to progress to the final four, sealing her semifinal berth with a down-the-line winner.

"I think there were just a few points difference," she said. "I was coming in with great shots, she was coming with better shots. In the end, sometimes I was winning the points, sometimes she was just playing incredible."

The WTA World No.17 concluded by looking forward to the next round: “I know tomorrow it’ll be a tough battle, but I’m sure this match will give me a lot of confidence.”